Means for doffing a bobbin and forming a transfer tail

ABSTRACT

In a spinning frame, or the like, a filled bobbin and its trailing bobbin thread are simultaneously removed from a spindle in a single doffing operation. At least one turn of the trailing thread is then wound as a transfer tail on the cleared spindle in a position to be pinched by the empty bobbin being donned in order to couple the thread to the donned bobbin. The thread is then severed near the spindle between the spindle and the bobbin.

United States Patent 3,696,602 Olson et al. [451 Oct. 10, 1972 [54] MEANS FOR DOFFING A BOBBIN AND 3,546,870 12/1970 Schewe et ..57l53 X FORMING A TRANSFER TAIL 2,653,440 9/1953 Partington ..57/53 3,280,545 /1966 King et al. ..57/53 72 l t ymon Harol 1 {11 gg g'jgfm d 3,394,539 7/1968 Morikawa ct al..............57l53 [73] m Barbe-Colman my Primary Examiner-Donald E. Watkins Rockford, Attorney-A. Richard Koch [22] Filed: Aug. 27, 1970 Cr [21 Appl. No.1 67,367 1 ln a spinning frame, or the like, a filled bobbin and its trailing bobbin thread are simultaneously removed (52 us. Cl. .57/53, 57/34 Tr, 242/18 PW from a spindle in a single doffing operation [em [51 lnLCl. ..D0lh 9/10,D0lh /00 one mm of the trailing thread is up wound as a 58] me bi sbmh ..s7/34 T112525 52, 34; transfer tail on the cleared spindk in a position m be 8 w pinched by the empty bobbin being donned in order m 56 Rd CM couple the thread to the donned bobbin. The thread is l 1 mm then severed near the spindle between the spindle and UNITED STATES PATENTS the bobbin- 3,552,110 lll97l Livingston ..57/53 14 Claims, 8 Drawing Figures 4 '1 L J u fix I 0 u 0 g g 512. J/ 7 6 m 6'3 F A L L a/ 0 OJ I i o 12M K j 95 j J E 17 7 H 5 790i 1 5 it 3; 1

1 2s 9 7 W m) a 61 i ii /5 p a m l7 j 56 57 -86 as PATENTEBocI 101912 3.896.802

sum 1 or 4 INVENTOR5 RAYMOND E OLSON HAROLD R. our

AGENT PATENTED an m we SHEET 2 BF 4 You:

INVENTORS HAROL 0 R.

FA YMdA/D 5. OL 50! AGENT PATENTEBum 10 m2 SHEET 3 0F 4 INVENTOR RAYMOND f. OLsoN HAROLD R. Yams AGENT PMEN'TEDuur 10 m saw u or 4 VENTORj RAYMOND OLSON HAMLD R. Yo %fl4/ AGENT MEANS FOR DOFFING A BOBBIN AND FORMING A TRANSFER TAIL BACKGROUND OF THE INVENTION This invention is concerned with spinning frames in which roving is drawn and spun into thread, the thread being wound on a rotating bobbin for future use. When a bobbin is filled with thread, it is doffed and an empty bobbin is donned. The bobbins are telescoped over and frictionally coupled to rotating spindles, which are stopped while bobbins are being doffed and donned. The thread has been coupled to the empty bobbin by winding several turns of thread as a transfer tail around the spindle in such a position that it is pinched between the spindle and the empty bobbin being donned. Placement of the transfer tail on the spindle has been accomplished automatically, as the filled bobbin was doffed by an impact delivered to the butt end of the bobbin, before the supply yarn was severed. During the doffing, several turns of thread were unwound from the fill bobbin and simultaneously transferred to the spindle to form a new transfer tail as the bobbin was popped off of the spindle. After the new transfer tail was formed, it was severed from the doffed bobbin and the empty bobbin was donned. The old transfer tail, trailing behind the bobbin being doffed, was caught by the turns of the new transfer tail, resulting in breakage of the old transfer tail from the tilled bobbin and the accumulation of such old trails on the spindle, where they eventually prevented proper seating of an empty bobbin and had to be removed by hand.

Richard D. Livingston, in a copending patent application Ser. No. 593,536, filed Nov. 10, 1966, now US. Pat. No. 3,552,110, issued Jan. 5, l97l, disclosed a method and means for mechanically removing the old transfer tail from the spindle as each bobbin was doffed. This eliminated the need for periodic removal of the accumulated old transfer tails from the spindle, but required a separate operation and apparatus to remove it. In doffing the filled bobbin, the energy stored in a powerful spring was employed to throw the bobbin off of the spindle. When expansion of the compressed spring was arrested, both dofi'er and spinning frame were violently shaken and considerable noise was created.

SUMMARY OF THE INVENTION The present invention is concerned with an automatic doffer used in combination with a spinning frame, or the like, for dofiing filled bobbins and donning empty bobbins so that there is no accumulation of old transfer yarn tails on the spindles, where they may interfere with the donning of empty bobbins or break the transfer yarn during dotting.

It eliminates the need for periodically removing the accumulated old transfer yarn tails from the spindles.

Damage to the butt end of the bobbin due to impact by the ejecting finger is eliminated.

The doffing action is more positive, permitting better control to be exercised.

The spring power required in doffing the filled bobbins has been reduced, substantially eliminating the shaking of the spinning frame and doffer.

Noise resulting from the dotting operation has been substantially reduced.

The mechanism required has been simplified.

The mechanism is less expensive.

The number of operations has been reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmental section through a spinning frame and automatic doffer showing the interaction between them in a preferred embodiment of this invention.

FIG. 2 is a partial elevation of the doffer as seen from the side adjacent the spinning frame and showing the driving connection between the doffer and spinning frame.

FIG. 3 is a plan view of the slack forming mechanism of the doffer taken along the line III III of FIG. 2 and showing the bobbins and related components of the spinning frame.

FIG. 4 is a fragmental isometric view of the relationship between certain components during the slack forming operation.

FIG. 5 is a fragmental isometric view of the relationship between certain components during the dofiing operation.

FIG. 6 is a fragmental isometric view of the relationship between certain components during the thread coupling operation.

FIG. 7 is a plan view of the ejection means with the ejector finger in extended position and showing its relationship to certain components on the spinning frame.

FIG. 8 is an elevation of the ejection means, partially broken away, and showing its relationship to certain components on the spinning frame.

Some of the figures have been used to demonstrate a plurality of operations. In such figures, there may not be correspondence between the positions occupied by components employed in one operation and those employed in other operations with respect to time.

DESCRIPTION OF THE PREFERRED EMBODIMENT While only one embodiment of this invention as applied to a continuously moving automatic doffer in combination with a spinning frame is described, it will be readily apparent to those skilled in the art that many modifications may be made in the described apparatus and that the invention may be adapted for use on automatic dofiers that stop at each station and in combination with winders, twisters and similar take-up winding machines in which a transfer tail is used to couple the filament, yarn, wire, etc. to a donned bobbin without departing from the inventive concept, the scope of which is limited only by the claims.

GENERAL DESCRIPTION Let us assume that a conventional spinning frame 1 is in operation and that, as shown in FIG. I, roving 2 is being drawn through drafting rolls 4 by feed rolls 5, to become supply yard 6. The supply yarn is passed through thread eyes 7 on pivoted lappets 8, and travelers 9 moving on guide rings 10, before being spun and wound as thread on bobbins 11. The bobbins are rotated by spindles 12, driven through clutches (not shown). The guide rings 10 surround respective spindles and are mounted on a ring rail 13, which is raised and lowered to distribute the thread along the bobbin. When the bobbins are filled, the ring rail 13 is dropped so that a number of turns of thread form a base bunch 14 just above the butt end 15 of the bobbin 11. The clutches are disengaged to halt spindle rotation while the filled bobbins are doffed and empty bobbins are donned by an automatic doffer 16 moving on a rack 17 down the row of bobbins on the spinning frame. The foregoing is well known in the art and will not be described in further detail.

As the doffer 16 moves along the rack 17, a camshaft 18 is rotated in synchronism with the progress of the doffer along the rack from station to station on the spinning machine. A pinion 19 fixed on the camshaft and engaging the rack causes the camshaft to make one revolution as the doffer moves from one station to the next, the distance between stations corresponding to the spacing between successive spindles 12 on the spinning frame 1. As the doffer 16 passes a predetermined position with respect to each spindle 12, a slack forming means 20 goes into action to provide slack 21 in the supply yarn 6, which slack is required for ensuing operations. The method and apparatus employed to provide the slack is described in detail later on.

After the slack 21 has been provided, lappet 8 with attached thread eye 7 is raised to the position shown in FIGS. and 6 by a cam (not shown) on the doffer 16 to prevent interference with the subsequent doffing and donning operations.

An ejection means 22, mounted on the doffer 16, comprises an ejector finger 23 that engages the butt end of bobbin ll, pries the bobbin loose from the spindle l2, and accelerates it upwardly off of the spintile.

The continuous engagement of the bobbin 1] with the ejector finger 23 throughout its stroke, which is a substantial portion of the full length of the spindle 12, prevents thread from unwinding from the base bunch 14 to form a new transfer yarn tail 25 on the spindle 12 during the doffing operation. It is because of this that slack 21 had to be provided to prevent breakage and the resultant loss of control of the supply yarn 6. The new transfer yarn tail must therefore be wrapped on the spindle in a separate operation. The wrapping means 26, mounted on the doffer 16, comprises a wrap around finger 27 which guides the trailing bobbin thread 28 between the doffed bobbin 1! and traveler 9 over and around the spindle 12 to wrap a new transfer tail 25 on the spindle.

An empty bobbin 11 is then donned, pinching the tail 25 against the spindle 12 as the bobbin is telescoped over and pressed downward on the spindle in conven tional fashion, which, forming no part of the invention, will not be further described.

SLACK FORMING MEANS As seen in FIG. 2, a pay off roll 29 is supported for rotation about its axis in a forked bearing 30 pivoting around a vertical shaft 31 parallel with the roll on the doffer 16. The fork 30 is biased by springs 32 toward the row of bobbins 11, so that the roll 29 frictionally engages the filled bobbins and follows their surfaces as the doffer moves down the row. The shah 31 is driven as by mating bevel gears 33 from the camshaft 18, as seen in FIG. 1. FIG. 3 shows sprockets 34 and 35 connected to the roll 29 and the shaft 31 respectively and interconnected by a chain 36, so that, as the doffer l6 advances down the row of bobbins 11 on the spinning frame 1, the roll is continuously rotated in a direction to unwind slack 21 from the base bunch 14 of the bobbin with which it is in engagement.

At substantially the same time that the roll 29 begins to unwind slack 21 from a given bobbin ll, slack fingers 37 and 38 engage the supply yarn 6 supplied to that bobbin on opposite sides of the thread eye 7. The slack fingers are pivotally mounted on a slack arm 39 and biased by a torsion spring 40 against a stop 41, as shown in FIGS. 2 and 3. The arm 39 is in turn pivotally mounted on the dofi'er 16 and biased by a torque spring 42 against a stop, as in FIG. 3, in which the slack fingers will engage the supply yarn 6 and pull along the slack 21 unwound from the bobbin 1] by the pay off roll 29 as the dotfer moves down the spinning frame 1. The spring 40 allows the fingers to hold the slack taut, while providing lost motion between the fingers and the arm 39 to prevent thread breakage if insufficient slack is available to be taken up by the movement of the doffer. A slack release cam 43, mechanically coupled by any suitable motion transmitting means 44 to shaft 31, so that it makes one revolution as the doffer moves between adjacent stations, engages an extension 45 of arm 39 to briefly retract the arm to the phantom position 39 in FIG. 3 and so release the slack 21 from the fingers 37 and 38 before the fingers arrive at a position to engage the next supply yarn 6. When the slack is released, it temporarily takes the form of the twisted loops seen in FIG. 5.

EJECTION MEANS The ejection means 22 is mounted on the doffer 16, as best seen in FIG. 2, which shows the ejection means in its inactive position. The ejector finger 23 is on one end of an ejection lever 46, movable about a point intermediate its ends on a pivot 48, perpendicular on an ejector arm 49. A torsion spring biases the lever counterclockwise as seen in FIG. 7, so that the finger is urged in the direction of movement of the doffer. Counterclockwise movement is limited by an ejector lever stop 51 integral with the ejector arm 49. The ejector arm is affixed on a rockshaft 52 pivoted in fixed bearings 53, and is biased to rotate counterclockwise, as viewed in FIG. 2, by ejector spring 54, the counterclockwise motion being limited by a resilient stop 55 seen in FIG. 8. A rocker arm 56 is also affixed to the rockshaft 52.

An ejector advance mechanism 57, best seen in FIG. 8, comprises an advance cam 58 on the camshafl 18, an advance cam follower 59 pivoted on an axis 60, and advance arm 61 integral with the follower and extending beyond the axis, and a link 62 connecting the advance arm to the rocker arm 56. When the cam rises, the link pulls the rocker arm downward, storing energy in the ejector spring 54 and moving the finger 23 downward. The downward movement of the finger is timed so that it enters between the guide ring 10 and bobbin l1 and continues until 3. lug 24 on the end of the finger is below the butt end 15 for each bobbin as the doffer 16 advances.

After the finger 23 has been lowered to bring the lug 24 below the butt end 15, the continues movement of the doffer 16 to the right as seen in FIG. 7 brings the lug under and the finger into lateral contact with the butt end. Thereafter, until the bobbin l1 and its old transfer tail 25 have been ejected from the spindle 12, continued movement of the dofi'er results in clockwise movement of the lever 46 as permitted by the torsion spring 50 while the finger maintains contact with the butt end. The contour of the advance cam 58 permits the ejector spring 54 to raise the lug 24 into contact with the butt end and to maintain such contact while the bobbin 1 l is being pried loose from the spindle 12.

The bobbin 11 is loosened from the spindle 12 by a pry mechanism 63 consisting of a pry cam 64 on the crankshaft 18, a bellcrank 65 following the contour of the pry cam in response to the urging of tension spring 66 and engaging a flange 67 on the rocker arm 56. The contour of the pry cam is such that a rise exerts a positive upward pressure on the flange through the bellcrank and so moves the lug 24 positively upward to pry the bobbin loose from the spindle after the ejector advance mechanism 57 has raised the lug into contact with the butt end 15.

At approximately the same time as the bobbin 11 is pried loose from the spindle 12, the advance cam follower 59 goes over a drop off 68 on the advance cam 58, releasing the ejector spring 54 to accelerate the ejector arm 49 upwardly in an arc and so move the ejector finger 23 and lug 24 upward parallel to the spindle. The lug carries the bobbin ll upward with the same accelerated motion. When the upward stroke of the lug is terminated by contact of the arm with resilient stop 55 at the position identified as 49, the momentum of the bobbin carries it off the spindle 12, through a chute 69, seen in FIG. 1, and against a dampener 70, which brings it to a cushioned stop in position to be seized by clamp jaws 71 in their extended positions 71. The stroke is long enough to prevent the trailing bobbin thread 28 from wrapping around the spindle as the bobbin is ejected.

As the lug 24 reaches the end of its upward stroke, the ejector lever 46 is retracted by a retract mechanism 72 to the position identified as 46' in FIG. 7 to prevent the lug from marking the spindle 12 as the doffer 16 advances. The retract mechanism 72, as seen in FIGS. 7 and 8, comprises a primary cam 73 on the camshaft 18, a primary cam follower 74, a retractor cam 75 rigid with the primary cam follower, and a retractor cam follower 76 on the other end of the ejection lever 46. The primary cam follower pivots on an axle 77 and is pressed against the primary cam by a bias spring 78. When the time to retract the lever arrives, a rise on the primary cam rotates the retractor cam clockwise to the position 75' in FIG. 2. This results in the retractor cam follower moving to position 76 and retracting the ejector lever. After the dofi'er has moved far enough so that the lug will clear the spindle, a dip in the primary carn permits bias spring 78 to return the retractor cam to its normal position, and so allows the ejector lever to resume its extended position.

WRAPPING MEANS The wrapping means 26 comprises a thread locating mechanism 79 and a wrap around mechanism 80.

A pair of thread locating fingers 81 in the locating mechanism 79 are pivoted on a stud 82 affixed to the doffer 16 and operated in scissor-like fashion through a series of links and levers 83 from the locating cam follower 84, pivoted on lever shaft 85 and riding on locating cam 86 on camshaft 18. After the bobbin 11 has been doffed and seized by the clamp jaws 71, the jaws are moved by mechanism not shown to bring the bobbin into the position 11', as seen in FIGS. 1 and 5, with the trailing bobbin thread 28 between the normally open locating fingers and against an abutment 88. The fingers are then closed loosely on the thread in response to motion of the cam to definitely locate the thread at a definite position between the closed fingers.

in the wrap around mechanism 80, seen principally in FIGS. 1 and 2, the wrap around finger 27 is pivoted about one axis on a hinge 89 for movement in a plane parallel to the direction of movement of the doffer 16. The hinge is fixed on a shaft 90 providing a second axis journaled on the doffer l6 and moved to cause movement of the finger in a plane perpendicular to movement of the doffer by a perpendicular arm 91 in response to a perpendicular cam follow 92, pivoted on lever shaft 85 andriding on perpendicular cam 93, the motion being transmitted through an assembly of links and levers 94. A similar combination of links and levers 95 transmits motion from a parallel cam follower 96, pivoted on lever shaft 85 and riding on parallel cam 97 to a parallel bellcrank 98 connected by a parallel link 99 to the wrap around finger 27. The upper end of the wrap around finger 27 is formed as a shallow V in a substantially horizontal plane above the locating fin gers 81. There is a notch 100 at the nadir of the V to retain the trailing bobbin thread 28, as will be ex plained later. The wrap around finger is normally positioned so that the notch 100 is directly behind the trailing bobbin thread as positioned by the locating mechanism 79. After the thread has been located, the finger is moved forward by the perpendicular cam 93 to catch the thread in the notch, after which continued forward movement of the finger pulls the thread from between the locating fingers. The contours of the perpendicular and parallel earns 93 and 97 are such that the notch is moved forward and backward and from side to side above the end of the cleared spindle 12 in such a relationship that the thread is wrapped around the spindle at least once to create a transfer tail 25 as the doffer l6 progresses. Because the position of the traveler 9 is not fixed, it is necessary that the notch make at least two circles around the spindle in order to assure a transfer tail of at least one turn.

After the new transfer tail 25 has been created, the locating fingers 81 are opened and the wrap around finger 27 is withdrawn to its normal position, freeing the trailing bobbin thread 28. A bar 101 engages the thread above the spindle 12 and drags it down to the position 28', where it is severed by a shear 102 near said spindle. An empty bobbin 11 is then donned, pinching the transfer tail 25 against the spindle to couple the supply yarn 6 to the bobbin, after which the lappet 8 and attached thread eye 7 are lowered and the clutch is engaged to restart the spinning operation. The mechanism for dragging down and severing the trailing bobbin thread, donning the bobbin, and lowering the lappet are mounted on the doffer and are conventional well-known apparatus that form no part of the invention, so they will not be described. The clutch is on the spinning frame and also forms no part of this invention.

Although the preferred embodiment is concerned with spinning yarn, the invention has other applications as previously noted involving filament, wire, etc. Realizing that filament has been used in the textile industry in reference to extruded or drawn plastics, it is to be understood that, when filament" is used in the claims, it is in the generic sense to cover yarn, thread, cord, string, rope, strand, fiber, wire, strip, or any other elongated flexible part that may be wound on a bobbin, or the like whether the filament is unitary or comprised of a plurality of components.

We claim:

I. An automatic doffer for use with a machine having a spindle for telescopic reception and rotation of a bobbin on which a filament is wound, the filament coupled to the bobbin by a transfer tail of said filament pinched between the butt end of said bobbin and the spindle, said doffer comprising an ejection means maintaining engagement with said butt end for a substantial portion of the full length of said spindle while ejecting from the spindle in a single operation both said bobbin and the filament trailing from said bobbin, whereby simultaneous wrapping of the trailing filament around the spindle is prevented.

2. An automatic doffer according to claim 1, said ejection means comprising an ejector finger maintained in continuous engagement with said butt end while both prying the bobbin loose from said spindle and accelerating the bobbin off of said spindle.

3. An automatic doffer according to claim 1 in which operation of said ejection means is synchronized with movement of the doffer with respect to said machine.

4. An automatic doffer according to claim 1, said ejection means comprising an ejector finger inserted under said butt end, a pry mechanism positively moving the finger upward in engagement with said butt end to pry the bobbin loose from the spindle, and an ejector spring accelerating said finger upward in engagement with said butt end for said substantial portion of the full length of said spindle after the bobbin has been loosened.

5. An automatic doffer according to claim 1, said ejection means comprising an ejector finger, an ejector spring, an advance mechanism moving said finger downward and storing energy in the ejector spring, means biasing said finger into lateral engagement with the butt end, a pry mechanism moving said finger positively upward, a retract mechanism moving said finger away from the spindle in opposition to said biasing means, and means synchronized with movement of said doffer with respect to the machine whereby the finger is sequentially moved downward by the advance mechanism, moved under the butt end, biased into engagement with said butt end, moved positively upward by the pry mechanism to loosen said bobbin on the spindle, accelerated upward by release of the energy stored in the spring, and retracted by said retract mechanism.

6. An automatic doffer according to claim 5, said ejection means further comprising an ejector arm, and a pivot perpendicular on the am, said pry mechanism and said ejector spring moving the arm upwardly in an arc, said ejector finger movable about said pivot, the biasing means being a biasing spring urging said finger in the direction of movement of said dofl'er, whereby the finger is maintained in engagement with said butt end as the doffer advances and the arm moves upi xl t f t ri tic doffer according to claim 1 additionally comprising means for subsequently wrapping a new transfer tail on said spindle after the bobbin has been ejected.

8. An automatic dofi'er according to claim 7, in which operation of said wrapping means is synchronized with movement of the dofier with respect to said machine.

9. An automatic doffer according to claim 7, said wrapping means comprising mechanism for locating the filament trailing from the ejected bobbin and a wrap around finger to catch the located filament and to move over and around said spindle to wrap the filament around said spindle and so form the new transfer tail.

[0. An automatic doffer according to claim 9, said wrap around finger mounted for movement about two axes perpendicular to each other, a pair of cams synchronized with movement of the doffer with respect to said machine, motion transmitting means connecting said finger to the respective cams to control motion of said finger about said axes.

11. An automatic doffer according to claim 10, said cams contoured to cause the finger to catch the located filament, pull said filament from the locating mechanism, and form said new transfer tail.

12. An automatic doffer according to claim 1 additionally comprising means for producing slack in said filament before the bobbin is ejected.

13. An automatic doffer according to claim 12, said slack producing means comprising means for unwinding some of the filament from said bobbin.

14. An automatic doffer according to claim 12, said slack producing means comprising a pay off roll in frictional engagement with said bobbin and rotating said bobbin in a direction to unwind some of the filament therefrom.

l III I i i 

1. An automatic doffer for use with a machine having a spindle for telescopic reception and rotation of a bobbin on which a filament is wound, the filament coupled to the bobbin by a transfer tail of said filament pinched between the butt end of said bobbin and the spindle, said doffer comprising an ejection means maintaining engagement with said butt end for a substantial portion of the full length of said spindle while ejecting from the spindle in a single operation both said bobbin and the filament trailing from said bobbin, whereby simultaneous wrapping of the trailing filament around the spindle is prevented.
 2. An automatic doffer according to claim 1, said ejection means comprising an ejector finger maintained in continuous engagement with said butt end while both prying the bobbin loose from said spindle and accelerating the bobbin off of said spindle.
 3. An automatic doffer according to claim 1 in which operation of said ejection means is synchronized with movement of the doffer with respect to said machine.
 4. An automatic doffer according to claim 1, said ejection means comprising an ejector finger inserted under said butt end, a pry mechanism positively moving the finger upward in engagement with said butt end to pry the bobbin loose from the spindle, and an ejector spring accelerating said finger upward in engagement with said butt end for said substantial portion of the full length of said spindle after the bobbin has been loosened.
 5. An automatic doffer according to claim 1, said ejection means comprising an ejector finger, an ejector spring, an advance mechanism moving said finger downward and storing energy in the ejector spring, means biasing said finger into lateral engagement with the butt end, a pry mechanism moving said finger positively upward, a retract mechanism moving said finger away from the spindle in opposition to said biasing means, and means synchronized with movement of said doffer with respect to the machine whereby the finger is sequentially moved downward by the advance mechanism, moved under the butt end, biased into engagement with said butt end, moved positively upward by the pry mechanism to loosen said bobbin on the spindle, accelerated upward by release of the energy stored in the spring, and retracted by said retract mechanism.
 6. An automatic doffer according to claim 5, said ejection means further comprising an ejector arm, and a pivot perpendicular on the arm, said pry mechanism and said ejector spring moving the arm upwardly in an arc, said ejector finger movable about said pivot, the biasing means being a biasing spring urging said finger in the direction of movement of said doffer, whereby the finger is maintained in engagement with said butt end as the doffer advances and the arm moves upwardly in said arc.
 7. An aUtomatic doffer according to claim 1 additionally comprising means for subsequently wrapping a new transfer tail on said spindle after the bobbin has been ejected.
 8. An automatic doffer according to claim 7, in which operation of said wrapping means is synchronized with movement of the doffer with respect to said machine.
 9. An automatic doffer according to claim 7, said wrapping means comprising mechanism for locating the filament trailing from the ejected bobbin and a wrap around finger to catch the located filament and to move over and around said spindle to wrap the filament around said spindle and so form the new transfer tail.
 10. An automatic doffer according to claim 9, said wrap around finger mounted for movement about two axes perpendicular to each other, a pair of cams synchronized with movement of the doffer with respect to said machine, motion transmitting means connecting said finger to the respective cams to control motion of said finger about said axes.
 11. An automatic doffer according to claim 10, said cams contoured to cause the finger to catch the located filament, pull said filament from the locating mechanism, and form said new transfer tail.
 12. An automatic doffer according to claim 1 additionally comprising means for producing slack in said filament before the bobbin is ejected.
 13. An automatic doffer according to claim 12, said slack producing means comprising means for unwinding some of the filament from said bobbin.
 14. An automatic doffer according to claim 12, said slack producing means comprising a pay off roll in frictional engagement with said bobbin and rotating said bobbin in a direction to unwind some of the filament therefrom. 